For the determinist or incompatibilist, there is no longer a debate about sexuality or gender identity being a choice. We know that free will is an illusion and with this knowledge people will no longer blame those who don't fit into their traditions of what a man or woman is. People may still disagree on the different labels attached to gender but they don't need to hate each other for what isn't really up to them in the first place.
As George mentions, the subject of whether something is wrong is separate from the debate on whether it is a choice. Something can be wrong or immoral if it causes harm. So the point is that while no one is choosing their gender identity or sexual orientation, people in society still may have disagreements on what behaviors are good or bad.
For a related video, see this old video by Zinnia Jones: https://www.youtube.com/watch?v=Z_hNwNScw1I